1. Field of the Invention
The present invention relates to a continuous rolling mill equipped with horizontal roll stands and vertical roll stands arranged in series in an alternating manner. More particularly, the invention is concerned with a continuous rolling mill which is improved to facilitate the renewal of the rolls and the rolling guides incorporated in the roll stands.
2. Description of the Prior Art
A known continuous rolling mill such as, for example, a continuous finishing rolling mill for billet is equipped with a plurality of horizontal roll stands each having two horizontal rolls and a plurality of vertical roll stands each having two vertical rolls. The horizontal roll stands and the vertical roll stands are arranged alternatingly along the rolling path, with a rolling guide disposed between two adjacent roll stands. In this type of continuous rolling mill, it is desirable to decrease as much as possible the temperature drop of the billet during the rolling; this saves energy, and reduces the housing space and the cost for the fundamental construction.
These requirements, however, could not be fully met by the conventional continuous rolling mill due to the fact that, in the conventional continuous rolling mills, the respective roll stands arranged at a predetermined pitch or interval are movable independently in the direction which crosses the rolling line toward the roll and rolling guide exchanging positions. This problem will be explained in more detail hereinunder. Namely, in the continuous rolling mill, it is necessary to employ rolls of different sizes and rolling guides of different sizes in conformity with, for example, the size of the billet to be rolled. In order to achieve a high efficiency of the work for changing the rolls and rolling guides, it is desirable to extract all of the roll stands at one time to the exchanging position, i.e. to pull and move all roll stands in the direction perpendicular to the rolling line. In the conventional continuous rolling mill in which the roll stands are extractable independently, the space between two adjacent roll stands is utilized as a stand-by space for the roll stands to be substituted for the extracted roll stands. In exchanging the roll stands, the old roll stands are demounted by the movement in the extracting direction and then the new roll stands are moved from the stand-by positions to the mounting positions. Thus, in the conventional continuous rolling mill, it has been necessary to preserve, between each two adjacent roll stands, a distance of a length corresponding to the width of the roll stand. Namely, it has been difficult to reduce the pitch or interval of the roll stands to a size smaller than the width of the roll stand.
Japanese Patent Application, Laid-open No. 39014/1982 (Application No. 113489/1980) discloses a continuous rolling mill having a roll exchanging system improved to shorten the roll exchanging time, wherein the driving units for the horizontal and vertical roll stands are arranged in a staggered manner in the vertical and horizontal directions to reduce the pitch or interval of the roll stand arrangement, and wherein all roll stands are mounted on a single truck. For exchanging the rolls, the roll stands are moved at once by the truck to the roll exchanging position where new roll stands carrying new rolls and mounted on another truck are ready for exchanging, and the old roll stands are exchanged with the new roll stands at once together with housings, thus completing the roll exchange in a shorter period of time. This system, however, uneconomically requires a preparation of another set of housings for the horizontal and vertical roll stands.